Modern local area networks (LANs) with their high bandwidths have become increasingly popular, especially with the advent of wireless LANs (WLANs). A WLAN permits handheld and portable computer users to connect to the LAN virtually anywhere in an office, in a building, or on a campus of buildings. The mobility of users requires that WLANs provide some level of interoperability so that a user located within range of one WLAN can move to within range of another WLAN and, in relatively seamless manner, be connected.
Security of WLANs is a consideration. WLANs are vulnerable to misuse by transient intruders, if access to the WLAN is not strictly controlled. An intruder with unfettered access potentially could download sensitive proprietary data from someone on the LAN or someone connected to the WLAN or could upload mischievous or dangerous data or software or could destroy data. Some access control methods identify the user requesting access, others require the user to prove his or her identity, and other, more secure, methods involve establishing a secure exchange of information before passing such information.
Network managers can make gaining unauthorized access to their WLANs more difficult by employing different protocols than other WLANs, but this approach can hinder the interoperability expected or relied upon by many users. At the lowest communication stack layer, changing the ‘chipping’ code of direct sequence or the ‘hopping’ sequence of frequency hopped spread spectrum WLANs allows the network manager to hide the manager's WLAN from unwanted intruders. Other layers in the communication stack are kept standard and interoperable. The security concerns of operators of WLANs have caused the WLANs, while nominally interoperable, to be incompatible or at least hidden from easy access by foreign (extra-organizational) wireless devices and users. Network managers typically do not want foreign users to consume resources and utilize Internet bandwidth provided for natives (users in the organization). WLANs have proven to be a popular and effective tool for data transfer to handheld and portable computer users residing natively on the WLAN.
Modern wireless wide area networks (WWANs) are also popular for their coverage of large geographic areas, such as cities, and for their penetration of buildings within the coverage area. In contrast to a LAN, a WWAN by its nature has data transfer rates that are lower owing to the limited bandwidth occupied by WWANs. The higher power utilized for wide area coverage is typically confined to smaller bandwidths to help keep transmitter power consumption reasonable and transmitter design practical. Thus, WLANs have high bandwidths over small coverage areas and WWANs have low bandwidths over large coverage areas.